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Thread: Logger wirtes zero values to file

  1. #1
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    Default Logger wirtes zero values to file

    Hi everyone,

    My logger writes a sequence of strings in a file by the java.io.PrintStream.println() method.
    In some case a line in log is formed by a sequence of zero values (that is 0x0, not zero in ASCII code, 0x30).

    I would like to know two things:

    1) In which cases it may happen?
    2) I would like to replicate the error: how can I do so as to write zero values in file?


    Thanks in advance for yours answers.

    Best regards,

    Matteo


  2. #2
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    Default Re: Logger wirtes zero values to file

    We will be able to help you more if you post some of the related code. 0x0 is the value for null. You can print null to a file by doing this println(null);
    I hope this helps.
    Last edited by theonlydvr; June 29th, 2013 at 02:47 PM. Reason: Better information

  3. #3
    Super Moderator pbrockway2's Avatar
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    Default Re: Logger wirtes zero values to file

    0x0 is the value for null. You can print null to a file by doing this println(null);
    I'm not sure that's right. As far as I know a PrintStream instance passed a variable or expression that evaluates to null will print the four letters "null" (which has the merit of being readable) and not the single letter 0x0.

    Also "println(null);" is ambiguous, you would have to cast the null to something. (Eg a String.)

    ---

    @OP: You are getting lines of the zero character because somewhere in the code you haven't posted you are telling the PrintStream instance to print them. You can do this, eg, by using the character literal '\0', or by using the same escape sequence inside a string literal:

    String str = "\0\0";
    System.out.println("The next line contains a couple of zero characters:");
    System.out.println(str);        
    System.out.println(str.length());

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